internal/rosa: do not register stage0

Nothing can depend on this, so remove it from the namespace.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/rosa.go

@@ -213,15 +213,12 @@ const (
 )
 
 var (
-	// The Mksh shell is added by [Toolchain.New] and used by almost all packages.
-	Mksh = H("mksh")
-	// Toybox is standard utilities added by [Toolchain.New].
-	Toybox = H("toybox")
-	// LLVM is the standard toolchain added by [Toolchain.New].
-	LLVM = H("llvm")
-
 	_stage0Dist  = H("stage0-dist")
+	_mksh        = H("mksh")
+	_toybox      = H("toybox")
 	_toyboxEarly = H("toybox-early")
+	_llvm        = H("llvm")
+	_patch       = H("patch")
 )
 
 // New returns a [pkg.Artifact] based on a [Toolchain] via s.
@@ -282,12 +279,12 @@ mkdir -vp /work/system/bin
 			name += "-std"
 		}
 
-		toybox := Toybox
+		toybox := _toybox
 		if flag&TEarly != 0 {
 			toybox = _toyboxEarly
 		}
 
-		base := LLVM
+		base := _llvm
 		if flag&TNoToolchain != 0 {
 			base = _musl
 		}
@@ -296,7 +293,7 @@ mkdir -vp /work/system/bin
 			cureEtc{newIANAEtc()},
 		},
 			base,
-			Mksh,
+			_mksh,
 			toybox,
 		))
 		env = fixupEnviron(env, []string{
@@ -326,8 +323,32 @@ mkdir -vp /work/system/bin
 	)
 }
 
-// patch is used by [Toolchain.NewPatchedSource].
-var patch = H("patch")
+// NewStage0 returns a [pkg.Artifact] curing to a stage0 distribution.
+func (t Toolchain) NewStage0() pkg.Artifact {
+	return t.New("stage0", 0, t.Append(nil,
+		H("bzip2"),
+	), nil, nil, `
+umask 377
+tar \
+	-vjc \
+	-C /stage0 \
+	-f /work/stage0-`+t.triple()+`.tar.bz2 \
+	.
+`, pkg.Path(fhs.AbsRoot.Append("stage0"), false, t.Append(nil,
+		_llvm,
+		_mksh,
+		_toyboxEarly,
+	)...))
+}
+
+// HasStageEarly returns whether a stage0 distribution is available.
+func (s *S) HasStageEarly() (ok bool) {
+	func() {
+		defer func() { ok = recover() == nil }()
+		s.New(stageEarly).MustLoad(_stage0Dist)
+	}()
+	return
+}
 
 // NewPatchedSource returns [pkg.Artifact] of source with patches applied. If
 // passthrough is true, source is returned as is for zero length patches.
@@ -365,7 +386,7 @@ cat /usr/src/` + name + `-patches/* | \
 		aname += "-patched"
 	}
 	return t.New(aname, 0, t.Append(nil,
-		patch,
+		_patch,
 	), nil, nil, script, paths...)
 }